Spatial distribution of lead in human primary teeth as a biomarker of pre- and neonatal lead exposure

Lead remains one of the most hazardous toxins in our environment. Because the toxic effects of lead are most prominent during early development, it is important to develop a suitable biomarker for lead exposure during the pre- and neonatal periods. In the present study, the spatial distribution of lead was measured in the enamel and dentine of ten human primary teeth using laser ablation-inductively coupled plasma-mass spectrometry. The neonatal line, visualized using confocal laser scanning microscopy, was used to demarcate the pre- and postnatal regions of the sample teeth. Lead levels in pre- and postnatally formed enamel and dentine were compared to blood-lead levels measured at birth and one year of age for four of these participants. Mean dentine-lead levels ranged from 0.17+/-0.02 to 5.60+/-1.79 microg/g, and mean enamel-lead levels ranged from 0.04+/-0.01 to 1.47+/-0.20 microg/g. The results of this preliminary study showed that the spatial distribution of lead in dentine reflected the blood-lead levels. The present study demonstrates a methodology where the spatial distribution of lead in the dentine of human primary teeth may be used to obtain temporal information of environmental lead exposure during the pre- and neonatal periods.     

Effects of Green Tea Extract and α‐Tocopherol on the Lipid Oxidation Rate of Omega‐3 Oils,Incorporated into Table Spreads,Prepared using Multiple Emulsion Technology

Abstract: This study examined the effectiveness of fat and water soluble antioxidants on the oxidative stability of omega (ω)‐3 rich table spreads, produced using novel multiple emulsion technology. Table spreads were produced by dispersing an oil‐in‐water (O/W) emulsion (500 g/kg 85 camelina/15 fish oil blend) in a hardstock/rapeseed oil blend, using sodium caseinate and polyglycerol polyricinoleate as emulsifiers. The O/W and oil‐in‐water‐in‐oil (O/W/O) emulsions contained either a water soluble antioxidant (green tea extract [GTE]), an oil soluble antioxidant (α‐Tocopherol), or both. Spreads containing α‐Tocopherol had the highest lipid hydroperoxide values, whereas spreads containing GTE had the lowest (P < 0.05), during storage at 5 °C, while p‐Anisidine values did not differ significantly. Particle size was generally unaffected by antioxidant type (P < 0.05). Double emulsion (O/W/O) structures were clearly seen in confocal images of the spreads. By the end of storage, none of the spreads had significantly different G′ values. Firmness (Newtons) of all spreads generally increased during storage (P < 0.05). Practical Application: Lipid oxidation is a major problem in omega‐3 rich oils, and can cause off‐odors and off‐flavors. Double emulsion technology was used to produce omega‐3 enriched spreads (O/W/O emulsions), wherein the omega‐3 oil was incorporated into the inner oil phase, to protect it from lipid oxidation. Antioxidants were added to further protect the spreads by reducing lipid oxidation. Spreads produced had good oxidative stability and possessed functional (omega‐3 addition) properties.     

Nalidixic acid resistance influences sensitivity to ionizing radiation among Salmonella isolates

Nalidixic acid (Nal) resistance has been used as a selective marker for studies of pathogen-inoculated fruits and vegetables. A collection of 24 Salmonella isolates were screened for natural resistance to Nal (50 microg/ml). The resistance to ionizing radiation was determined and compared for i) three naturally Nal-resistant (Nal(R)) strains, ii) three naturally Nal-sensitive (Nal(S)) strains, and iii) three strains derived from Nals strains that were made resistant to Nal (Nal(Ri)) by successive culturing and selection in Nal-amended broth. The radiation D10-values (the radiation dose required to achieve a 1-log reduction in population) were determined in buffer solution and in orange juice. D10-values were significantly (P < 0.05) different among the Salmonella isolates tested. When considered as a group, Nal(R) isolates were significantly more sensitive to ionizing radiation than Nals isolates in both media tested. In buffer, D10 of Nal(R) was 0.210 kGy versus 0.257 kGy for Nals. In orange juice, D10 of Nal(R) was 0.581 versus 0.764 for Nals. Inducing resistance to Nal altered the response to irradiation. D10-value of Nal(Ri) was 0.234 kGy in buffer, a 9% reduction relative to Nals parents. In orange juice, the D10-value of Nal(Ri) was 0.637 kGy, a reduction of 17% relative to Nals parents. These results suggest that natural and/or induced resistance to Nal may predispose Salmonella isolates to greater sensitivity to ionizing radiation,and that this effect is influenced by the suspending medium and by the nature of the isolates evaluated.     

Effect of κ-carrageenan on rheological properties, microstructure, texture and oxidative stability of water-in-oil spreads

The effect of κ-carrageenan concentration (0-7.5 g kg⁻¹) on the rheology, microstructure, texture and oxidative stability of water-in-oil (W/O) spreads (600 g fat kg⁻¹ emulsion) was examined over 60 days storage time. Results showed that increasing the κ-carrageenan concentration to 7.5 g kg⁻¹ significantly increased the viscosity of the aqueous phase (to 42.7 mPa s at 60 °C) resulting in gelation of the aqueous phase on cooling. The microstructure of the spreads was disrupted by higher levels of κ-carrageenan, resulting in a less homogeneous distribution of the aqueous phase. Melt temperature (where tan δ > 1) decreased significantly from 62 to 56.2 °C with increasing κ-carrageenan concentration from 0 to 7.5 g kg⁻¹. The firmness and the G′ at 6 °C for all samples were significantly increased after 60 days storage with only small effects due to κ-carrageenan levels. Oxidation of the fat phase was evident by the significant increases in peroxide values of all spreads on storage, with κ-carrageenan exhibiting no antioxidant behaviour. While increased κ-carrageenan levels modified the microstructure of W/O spreads in terms of the droplet size of the aqueous phase and its distribution few changes were evident in the continuous fat phase.     

Application of distance sampling techniques for diving ducks on Lake St. Clair and western Lake Erie

Lake St. Clair and western Lake Erie are important migration staging areas for diving ducks including canvasbacks (Aythya valisineria), redheads (Aythya americana), and lesser and greater scaup (Aythya affinis and Aythya marila). Starting in 1983, the Michigan Department of Natural Resources (MDNR) attempted to census diving ducks on the United States portion of Lake St. Clair throughout autumn migration; however, in 2010 the MDNR expanded the traditionally surveyed area to include all of Lake St. Clair and a portion of western Lake Erie. The idea of achieving a census over the expanded study area was unrealistic, and instead distance sampling techniques were adopted in an effort to generate statistically valid estimates of detection probabilities and abundances for diving ducks during spring and autumn migration. We found distance sampling techniques to be a viable option for estimating diving duck abundance as long as flock size is accounted for as a covariate affecting the detection function. Diving ducks were generally more abundant on our study area during autumn migration with a mean of 306,327 ducks/survey (SE = 40,729) compared to an average spring abundance of 91,053 ducks/survey (SE = 19,175). Peak abundance occurred on 20 November 2012 with an estimated 596,335 diving ducks on Lake St. Clair and western Lake Erie. Ultimately, our methodology could be used to establish long-term, standardized data collection techniques and applied to conservation planning for waterfowl in the Great Lakes region.     

A reservoir serves as refuge for adults of the endangered Macquarie perch

Home‐range estimates are an important input to species recovery plans. Our aim was to estimate the home‐range size of the endangered Macquarie Perch in the lower Cotter River catchment, Australia. In total, fourteen home‐range estimates were calculated from intensive radio‐tracking of adult individuals over a minimum of five diel periods in either autumn (n = 5) or spring (n = 9). Home‐range (95% Kernel) and core area (50% Kernel) were calculated by Kernel estimation and corrected for overlap with land. Seasonal estimates of home‐range and core area were not asymptotic in relation to cumulative number of radio‐fixes in four of fourteen cases. The mean within‐season home‐range of adult Macquarie perch was 5.5 ha ranging from 0.2 to 18.4 ha, based on 10 cumulative estimates that were asymptotic in relation to radio‐tracking effort. All five individuals radio‐tracked in autumn occupied a single core area, whereas in spring, six individuals occupied a single core area and three individuals each occupied three core areas. Despite individuals moving on a scale almost comparable to Cotter Reservoir (48.5 ha), only a single radio‐tagged individual was found to leave the reservoir and enter the river. Regional fisheries managers are generally aware of the requirement for Macquarie perch to access flowing water for spawning in south‐eastern Australia; however, in the Cotter River catchment, the protection of habitat for this species within Cotter Reservoir is also paramount. Our study highlights the importance of reservoirs for conserving a threatened aquatic species.     

Preparation of metal-aromatic diamine complexes and their influence on the cure of a commericial epoxy resin

Summary The preparation of metal-aromatic diamine complexes is reported along with their characterisation by infrared spectroscopy. Dynamic viscometry (gel-point determination) was used to assess the reactivity of some of the metal-diamine complexes with a commercial epoxy resin. Significant differences were observed in the viscosity profiles for formulations with different metal contents. These related to the reactivities of the diamines which are themselves a function of metal content.     

Informational basis for children's impressions of others.

Assessed the age at which 22 kindergartners, 22 2nd graders, and 22 5th graders used covariation information to form impressions of others when behavioral frequency was held constant or was varied. In Exp I the frequency of aggressive or helpful behavior was held constant, but behavioral consistency or nondistinctiveness was varied. Ss made single-rating and paired comparison judgments about each actor's future behaviors and personal characteristics. Results reveal that 2nd and 5th graders' comparison judgments were appropriately differentiated according to the available covariation information, whereas kindergartners' judgments were not appropriately differentiated. A 2nd experiment was conducted to determine whether 24 kindergartners' failure to use covariation information was simply the result of task demands. Ss made paired comparison judgments about aggressive behavior. Aggression frequency was either held constant (consistency vs nondistinctiveness) or was varied (relative degrees of consistency or nondistinctiveness). Results show that Ss' impressions of others did not vary according to differences in covariation information, at least when frequency was held constant. Findings undermine a task-demand interpretation of the results of Exp I and indicate that young children do use frequency information. There was no evidence that Ss used covariation information independently of differences in frequency. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)